Casting wheel



'oct 27, 1936. J H DOORBAR 2,058,670.

CASTING WHEEL Filed DeC. l, 1933 INVENTOR Bllm Hoarbar ATTORNEY Patented Oct. 27, 1936 UNITED STATES CASTING WHEEL John H. Doorbar, Highland Park, N. J., assigner to Du Pont Film Manufacturing Corporation, New York, N. Y., a corporation of Delaware Application December 1, 1933, Serial No. 700,602

Claims. (Cl. 18-15) This invention relates to an improved film-casting-Wheel and aims to provide such a wheel with a wear-resisting casting surface capable of imparting a high degree of uniformity and surface 5 smoothness to cast film.

Casting wheels have heretofore been made by plating a surface of copper on a wheel and then plating a layer of nickel on the copper to form the casting surface. The nickel surface is rather soft so that it does not wear well and quite frequently small metal crystals or flakes which have been formed during and as the result of the plating process, detach themselves from the casting surface with the result that thereafter the l5 casting surface is irregular and a blemish is caused in the film. It has been suggested to plate chromium on the nickel, but the chromium also akes to some extent. Furthermore, electro deposited surfaces must necessarily be thin to avoid imperfections and it thus becomes necessary to replate them from time to time due to the wearing through of the thin layer. Also, a metal wheel base having on its rim several thin adherent coatings of dissimilar metals does not make an ideal lm casting wheel, because the metals have different coefcients of expansion, and, when alternately heated and cooled, the thin layers are subjected to successive expansion and contraction whichbreaks or cracks them,

thus destroying the smooth surface as well as loosening the casting surface, and the lm which is thereafter cast on the wheel has blemishes in it.

The casting wheel which I have invented includes a wheel body with a peripheral casting surface of a sheet of corrosion resisting metal,

preferably a surface of stainless steel, which is extremely hard and resistant to all kinds of blemishes, and which does not become pitted during use. The stainless steel surface is relatively thick and may be laid directly on the wheel body thus eliminating the difficulty inherent in using several thin layers of electro deposited metal.

The steel is much stronger than any of the metals heretofore used for casting surfaces and there- 45 fore, even though it may have a coefficient of expansion which is slightly different from that of the Wheel body, it will not break. Furthermore, a stainless steel band of appreciable thickness may be keyed directly to the body of the wheel 50 and thus may be firmly fixed to the Wheel body. The stainless steel band may be and preferably is, manufactured so that it is very close grained, that is, so that it will not flake, and the diflculty inherent in the usual electro deposited surfaces 55 is overcome. Furthermore, as the stainless steel band is so very much thicker than any suitable electro deposited surface, it will Wear for a very much greater period of time than Will an electro deposited surface and can be used until it is worn down almost to the rim of the wheel body. As 5 it takes a considerable period of time and special apparatus to prepare a copper and a nickel casting surface and a considerably longer period of time to prepare a chromium surface, none of which surfaces will wear for the desired length l() of time, the advantage of having a surface which will Wear for a long period of time and which will not become pitted or blemished and which will be strong and which can be laid directly on the wheel body Without the use of special plating l5 apparatus, will readily be understood.

My invention can readily be understood by reference to the illustrative example shown in the accompanying drawing in which Fig. l` is a side view of the wheel with portions broken away 20 to show its construction, Fig. 2 is a detail of the weld as shown in Fig. l, and Fig. 3 is a detail of la modified form of the weld for the casting surface.

The wheel body is preferably a single casting 25 with spokes 2, extending outwardly from a central aring 4, to support the rim 6 of the body. The rim 6 of the wheel body, afterV being cast, is trued up with'the center line of the central bearing. Then a key-way or slot 8 is preferably, al- 30 though not necessarily, cut across the rim of the body and a key or lock I0 may be placed in the key-way. A sheet l2 of stainless steel or other hard and corrosion resisting metal is then placed around the wheel body. The casting Yband is 35 wide enough to extend to the sides of the rim 6 of the wheel body and is of such a length that when it is cold and drawn tightly around the rim 6 of the body, the ends I4 and I6 of the band lack a small fraction of an inch of `touching 40 each other. 'When the band is on the wheel, the band is preferably heated to expand it sufficiently for the ends of the band to come almost together, whereupon the ends are welded together while the band is hot, the welding material being indicated at I8. The band may conveniently be heated to expand it, by blow torches applied to its surface.

The Welding rod is preferably made of the same composition as the stainless steel band, except that it has a slightly higher carbon content than the ban-d. This excess carbon content is burned out during the welding operation so that the composition of the Weld is the same composition as the band. In the preferred form steel band. This welds together the ends of the band and also forms a key or lock which fastens the sheet of stainless steel to the wheel body. In

the form of wel-d shown in Fig. 3, a key or lock Van absolutely smooth casting surface.

I is placed in the key-way 8 and the Welding metal iswelded both tothe key and to the ends I4 and I6 of the stainless steel band.

After the ends of the band are Welded together,

ythe band is permitted to cool whereupon it shrinksv and holds itself firmly on the rim 6 of the wheel f body. The contraction of the band is usually sufficient to fix the band rmly to the-rim of the wheel body but with the welding metal weld--Y ed to the key or laid in the slot 8 to form the key,

an exceedingly strong welded junction is obtained Y which is also used to insure that the casting surface will not slipk on the rim 6 ofthe wheel body. After theband. I2 has been shrunk on to the Wheel body, aY rim flange 2II` may be weldedto the band, or the Aflange may be a part of the original wheel body casting.

Thecasting surface is then finished off in any suitable manner, as by cutting with metal tools or grinding, to true it with the bearing 4 and finally the casting surface is polished to provide If the Welding and finishing are properly done, the Weld cannot be'seen andV causes no irregularity in the casting surface;V As the final Weld is an integral part cf the steel casting surface and is yof the same composition, it Wears at'the same rate as therother portions of the casting surface and causes no blemishes in thenlm throughout the life of the casting wheel.V

- The preferred casting bandis a sheet of stainless steel of an iron-chromium-nickel alloy. The chromium may vary to 35% and the nickel may vary from 3 .to 25%. The alloy may also contain small amounts of carbon, manganese, phosphorous, sulphur andrsilica, but these metals usually do not run over 2% in their total amount. The remainder rof vthe alloy is iron. The stainless steel bandhas Such a crystalline structure that the crystals are Very closely knit and do not flake out or olf of the castingsurface and consequentlyy the film which is cast on such a wheel is without blemish. As the steel alloy is resistant to corrosion,it is unaffected by any of the usual chemicals which might happenrto come into contact with it,rthat is, any of the chemicals which arer used in'making the film dope orY which are used forcleaning the wheel or which Would ordinarily be used around a factory which produces films.

' Although stainless str-eel is the preferable-material for use as a casting surface, a nickel steel containing approximately 18% nickel may be used: as v,it `is practically non-corrosive.Y Also manganese Vsteel containing approximately 11 to 15% manganese with small amounts of carbon and silica may be used. A small amount of copper, usually less than 1%, in steel also retards Vgiven only by way of illustration and may be modified-in many particulars without departingV from the spirit of my invention, which I desire to be construed as broadly as the following claims, taken in conjunction with the prior art may allow.

What I claim is: Y

1. A wheel for casting films from solutions containing cellulosic derivatives, that comprises a wheel body having mechanically attached thereto a peripheral integral casting element of substantial thickness composed of nonflaking corrosion resisting steel, said casting element having itsfouter peripheral Vsurface finished to render it suitable for casting film, said wheel body andsaid casting' element havingsubstantially the same coefficient of expansion.

2. A Wheel for casting films from solutions containingcellulosic derivatives, that comprises Y a wheel body having mechanically attached there- Y to a peripheral integral casting VVelement of substantial thickness composed of nonfiaking corrosion resisting steel alloy, said casting element having `its vouter peripheral surface finished to render it suitable Yfor casting film, said wheel body and said casting element having substantially the same coefficient of expansion.

'3. A Wheel for casting films from solutions con-V Vtaining cellulosic derivatives, that comprises a Wheel body having mechanically attached thereto a peripheral integral castingl element of substantial thickness composed Aof nonfiaking corrosion resisting iron-chromium alloy; said casting element having its f outer peripheral" surface finished to render it suitable for casting film, said wheel body and -said casting element having substantially the'same coefficient of expansion.

4. A wheel Vfor casting films from solutionsfcontaining cellulosic derivatives, that comprises a wheel body having mechanically attached thereto a peripheral integral casting element of substantial thickness composed of nonfiaking corrosion Y resisting iron-chromium alloy containing from 5 to chromium,.,said casting element having its outer peripheral surface finished to render it suitable for casting film, said Wheel body and said casting element having substantially the same coefficient of expansion. f, Y

5. A wheel for casting films from solutions containing cellulosic derivatives, --that comprises a Wheel body having mechanically attached thereto a peripheralintegral casting element of substantial thickness Vcomposed of nonflaking corrosion resisting iron-chromium-nickel alloy containing fromu3 to 25% nickel, said casting element having its outer peripheral surface finished to render it suitable for casting film, said wheel body and said casting element having, substantially the same coefiicientof expansion.

JOHN H. DOOR'BAR.- 

